Users of business customer systems access a system operator or consult a printed telephone directory to obtain a desired telephone number. Alternatively, automatic directory assistance can be provided locally at the station set using a microcomputer having the capacity to store several hundred directory entries. An example is the memory access system disclosed in U.S. Pat. No. 4,341,929 issued to R. D. Alexander et al on Mar. 20, 1980. The Alexander et al device is accessed by inputting a name via an alphanumeric keyboard. A microprocessor accumulates the inputs and displays the name and assigned telephone number upon matching the inputted entries with one of the records stored in memory. A problem arises since it is quite expensive to provide such equipment at each station set. Moreover, it would be almost as expensive to provide an alphanumeric keyboard at each station for the purpose of providing centralized automatic directory assistance.
Accordingly, alternative arrangements have been devised to permit a user to operate a telephone type keypad as an alphanumeric keyboard. For example, operating the second keypad button is normally recorded as the number 2, however, if the star (*) button is operated prior to operating the second button then the letter A is recorded. If either the 0 or pound (#) button is operated prior to operating the second button, then the letter B or letter C is recorded, respectively.
An example of using a station set keypad in an alphanumeric mode is disclosed in U.S. Pat. No. 4,005,338 issued to R. R. Morley et al on Jan. 25, 1977. The Morley et al arrangement uses three additional buttons in place of the *, 0 and # buttons for differentiating between the letters assigned to a keypad button.
Using either of the above-mentioned keypad schemes in a station set directory assistance arrangement would be cumbersome, since inputting each letter of a sought after name requires the user to operate two keypad buttons. Also, failure to operate a button to differentiate between a group of letters, for example, the letters A, B and C, could cause the system to display the wrong telephone or station set extension number if such a failure results in a default to the first letter of the group.
An article entitled "Alphabetic Data Entry Via the Touch-Tone Pad: A Comment" by S. L. Smith and N. C. Goodwin, appearing at pages 189-190 of Human Factors, Vol. 13(2), April 1971, describes the use of a keypad pad for name inputting to a computer. A problem arises in using the Smith-Goodwin arrangement because all number coded letters of a name need to be inputted in order to receive a response from the arrangement. Thus, a user would be faced with an inordinate delay before receiving a response when inputting the number coded letters of a long name.